Wire coil insert



Nov; 2s, 1944l Q HMS 2,363,789

WIRE COIL INSERT Filed Des.` 16, 194s INVENToR. j orro HMS Biff/wa Sm Fig. 2. The rie/cess should be deep enough'so tira zscsnse wma con. mssa'r Richmond Hill, N. Y., assignor to cts Company, Inc., Long Otto Haas,

Aircraft Screw Produ Island City, N.Y a corporation of New York Application December 1 6, 1943, Serial No. ,514,438

' 5 claimt. (ci. ssa-4s) The present invention relates to wire coil infserts' for screw connections of the type described,

for instance in U. S. Patent No. 2,150,876 of March Wire coil inserts ofthe kind here under consideration require some integral means whereby x the coil can be contracted prior to insertion into the tapped' hole of a nut orboss member and it is essential for this purposethat a tool inserted in the coil can grip theend advancing into the tappedhole. It is also necessary that after removal of the inserting tool all the coil convo1u,

tions are free for engagement'. by the threading of a stud or bolt member. '.lhe well-known inserts are provided with a diametrical tang of its end convolution so arranged that the tang can be broken offl after the insertion of the coil is Y completed. In many instances, however, this is not a desirable design inasmuch as the tang constitutes a waste, as it is diilicult'v to break' the tang if the wire has a substantial thickness and as it is diiiicult in many instances to remove the broken tangwhen the hole into which the coil is-inserted is ablind one. 4

The present invention 'contemplates to provide means whereby the mentioned disadvantagescan be avoided and essentially consists in that one coil end isv provided with a recess on the inner side lof the convolution 'so that a hook-shaped end is produced which does not project from the desired shape of the coil. Further objects and details of the invention will be apparent lfrom the description given hereinafter and the accompanyin; drawing inustrating embodiments thereof by way of example. In the drawing, Y

Pig. l is a perspective view of a wirecoll according to the invention;

Fig. 2 is a irontv view of a modified portion of v the recessed end; and

Fig. 3 is a perspective view of another embodi4 men r v 'Referring now to the drawing,`Fig. 1 shows a wire coil in general denoted by I which'has a v diamond-shaped cross-section. However, it is to l be understood that the invention is applicable to, coils of wire cross-'section of any form such as round. square or pear-shapedy cross-section. The one end convolution 2 of the coil is provided with a recess 3 on its inner side andthe flank l of the recess close to the ultimate end of the convolution is located in a .plane substantially'radial With 'lpt V to the coil axis I. vIt is advantageous a in many to make the `mentioned dank undercut asl indicated at la inthe modincationof t a tool witha radial projection inserted into the `coil may engage the ilank 4 safely. On the other hand, sumcient material of the'recessed portion should remain to transmit the torque applied by 5 the tool at the ank l to thecoil convolutions in order to contract the coil for insertion. In most instances, a recess depth of approximately half the wire thickness will be adequate.

The end face 3 of convolution g may be slanted 1o so that an inner edge 1 is provided which may bolt screwed into the 4 l bite into the material of a insert-in order to'create a locking eiect.

In many instances it is dsirable to gradually decrease the diameterv of at least a 'portion of the end convolution which is leading in inserting the` coil in order to facilitate the engagement of the coil with the threading of the member into which it isto be inserted. In this evenhthe recess is provided in the portion of reduced ldiainetei. This lsshown in Fig. 3 where the larger coil body il is cylindrical whereas the end convolution |`2` is of decreasing diameter so that the end portion thereof projects inwardly with respect to the inner coil cylinder. It will be noticed that according to what has been stated about the coil wire cross-sections Fig. 3 showsa coil of round wire.

If an inwardly projecting coil end is provided it is advisable to haveitproject at least as faras the depth of the recess Il provided therein.l When after theinsertion of the coil in a boss member, a bolt or stud is screwed suillciently deep A into it, the bolt'or stud portion entering the mentioned end convolution will expand it so as to engage the boss threading the same as the re- 5 mainder of the coil. The recess I3 with its ilank Il Votherwise corresponds entirely to the recess 3 and flank I or la respectively of Fig. 1 or 2.

In producing an insert accordingto the inven'f tion I have found that it is advisable to provide 40 the recess after the wire has been wound into coil shape because recessing of the wire prior tothe coiling interferes with the uniform shaping of the coil owing to the fact that the stress disthat no particular dilculties are en countered in providing a recess according Ito the invention in a coil convolution which projects `inwardly as shown in Fig. 3. 'I'he providing of a recess in an end convolution of a coil cylindrlcal throughout as shown inFig. 1, however, requires a particular method because the tool used'in cutting or otherwise making the recess would be apt to interfere with the subsequent convolutions located onthe same cylinder as the coil tribution is not uniform in the recessed and the 45l non-recessed portions of the wire. It be tion, which shall be limited only by the scope end. VIn makinaa coil according to Pls. 1, I proceed therefore in such a manner that I ilrst wind the wire to form. a cylindrical coll, then I bend a portion of one end convolution approximately into the position asshown in Fis. 3 and thereafter apply a tool to recess the end. is completed, `I cause the inwardly projecting end to returnto its original position .either owing to.

the natural resiliency oi the wire material or by bending it back to the diameter o! vthe main coil body. Whether such restoring of the circular form of the end convolution requires a bending force or whether the resiliency oi the material is sumcient for this :purpose will, of course, depend on'the one hand on the quality of -the mattu'ialI and on the other hand on the length of the arc When the recessassenso y la substantially cylindrical wire coil, one end con- I a substantieuy eyiindncai wire een, a portion o:

or portion of the end convolution which has heen.`

bent inwardly for the application of the recessins tool.

` Although I have described my invention in relation to only two diilerent forms, it will be clear to those skilled in the art that alterations and modincations thereof may be made without departing from the spirit and essensce or the inventhe appended claims.

I claim: i i 1. An insert for a screw connection comprising:

O f. 25 said recess.

volution ot said coil being provided with a recess on its inner side near its free end, said recess having a depth of approximately half the wire thickness and having a substantially radial ilank adjacent to said free end so as to form' a hook for the ensement oi a torque-applying tool.'1 f

2. An insert as claimed in claim l wherein said ilankis undercut.

3. An insert as claimed in claiml l wherein said free end is tapered from the outside to the inside. 4. An insert for a screw connection comprising one end convolution of said coil havinga decreasing diameter so that it projects inwardly with respect to the inner coil cylinder, said projectins portion being provided with a reoesson its inner side near itslree end.' and said recess having a depth ot approximately halt the wire thicknsu and havins a substantially radial nank adjacent to said tree end.

5. An insert as claimed in claim 4 wherein said portion of one end convolution projects inwardly an amount approximately equal to the depth of 

